Introduction to herdr

herdr is an R package designed to calculate greenhouse gas (GHG) emissions and land use (LU) associated with livestock production. It offers a robust framework for environmental impact assessment based on animal physiology and diet composition.

Currently supported animals:

• 🐂 Cattle
• 🐐 Goat
• 🐑 Sheep

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📊 What the Package Calculates

The package models the primary sources of environmental impact from livestock based on a detailed Energy Balance model. It accounts for energy requirements for maintenance, growth, lactation, pregnancy, work, and wool production.

Methane ($CH_4$) Emissions

• Enteric fermentation: Emissions produced during the digestive process based on Gross Energy intake and diet digestibility ($Y_m$).
• Manure management: Emissions derived from Volatile Solids ($VS$) decay, adjusting for specific management systems (e.g., liquid lagoons, solid storage, pasture, composting).

Nitrous Oxide ($N_2O$) Emissions

• Direct: Emissions from manure storage and treatment systems.
• Indirect: Emissions via nitrogen volatilization ($NH_3$, $NO_x$) and leaching into water systems.

Land Use

• Calculates the land area ($m^2$) required to produce the feed based on economic allocation, linking animal intake directly to crop yields using FAOSTAT and BC3 databases.

Multi-Scenario Analysis

herdr allows you to model different farms, regions, or management strategies within the same project. You can compare results across different geographic scales or management intensities in a single run.

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🎯 Calculation Methodology (IPCC 2019)

All emission calculations within herdr adhere to the Tier 2 methods established by the Intergovernmental Panel on Climate Change (IPCC).

Specifically, we follow the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories: > “Volume 4: Agriculture, Forestry and Other Land Use, Chapter 10: EMISSIONS FROM LIVESTOCK AND MANURE MANAGEMENT”

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🥕 The Role of Diet & Validation

• Diet-Driven: Diet composition is the primary driver of the results, determining key parameters like the Methane Conversion Factor ($Y_m$) and Nitrogen Excretion ($N_{ex}$).
• Automatic Validation: Before calculating, herdr automatically checks the consistency of input data, ensuring that biologically implausible values (e.g., impossible intake relative to weight) are flagged.

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🚀 Getting Started

To begin using herdr, you need to install the package and initialize your workspace. We have prepared a comprehensive, step-by-step guide to help you set up your project, manage your data, and run your first assessment.

In the Workflow guide, you will find:

• 📥 Installation: How to install the package and avoid common Windows errors.
• 🛠️ Initialization: How to set up the folder structure with herdr_init().
• 📂 Data Management: A detailed walkthrough of the input CSV files (Census, Nutrition, Manure).
• 📊 Execution: How to run the final generate_impact_assessment().

👉 Go to the General Workflow Guide